


Binary Stars

by bluenebulae



Category: Avatar: The Last Airbender
Genre: Alternate Universe - Soulmates, Day 2: Counterpart, Enemies to Lovers, F/M, Inspired by The Night Circus, Zutara Week, Zutara Week 2020
Language: English
Status: Completed
Published: 2020-07-28
Updated: 2020-07-28
Packaged: 2021-03-05 19:53:46
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 9,644
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25560892
Author URL: https://archiveofourown.org/users/bluenebulae/pseuds/bluenebulae
Summary: Ever since she was a young girl, Katara’s grandmother had told her tales of the man she would one day kill.A soulmate AU, with a twist.
Relationships: Katara/Zuko (Avatar)
Comments: 44
Kudos: 383
Collections: Zutara Week 2020





	Binary Stars

Ever since she was a young girl, Katara’s grandmother had told her tales of the man she would one day kill.

The first time she heard of him was the night after she first bent water, shocking her whole family by melting a hole right through the wall of their igloo. There hadn’t been a waterbender born into their family in generations; her brother crossed his arms and sulked for the rest of the night, while her father and grandmother exchanged a glance that she wouldn’t understand for years to come. The next evening, as her father and Sokka trawled the ice for fish under the midnight sun, her Gran-Gran brewed Katara a cup of warm seal milk and explained:

“You have a gift, Katara. A gift that could save our tribe.”

“How?” Katara had asked. She still remembers, now, how proud she had felt, how important and how scared.

“Our village is not as strong as it once was. We lose warriors to the raids and the hunts, with no way to heal them. But a fully-realized waterbender, a master waterbender, can heal any wound.”

“I’ll become a master, then,” Katara had said, as if it were the easiest thing in the world.

“It’s not so simple, child,” her Gran-Gran had said. “You must train for many years. You must learn the art so well that it becomes a part of you. And once you have taken those lessons inside yourself, when the water is in your soul, you must seek out the fire within it and destroy it.”

It had been a gentle warning for a young girl. It had taken many years for Katara to understand the full scope of it, and she still hadn’t, not fully, until she traveled north to train under Master Pakku, where she was hopelessly lost among the conversations of students alluding to some mysterious, far-off confrontations with firebenders, the ones they called their counterparts.

When she returned home, she asked her Gran-Gran if she’d heard of the phrase. Gran-Gran had sighed heavily, infusing the sound with the weight of years, before setting down her soup bowl.

“Yes, child. But when I was your age, we called them something different. We called them soulmates.”

-

The legend goes like this: at the beginning of all time, before there were nations or wars or even elements, there was one spirit that contained all of the dualities of the world within it. But the other spirits feared its power, and in an effort to control it, they attacked. It began to splinter, and its energy infused every bender, giving them their power over their element.

The elements were never meant to be separated – earth and air, water and fire. Each air spirit has a corresponding earth spirit that roams the earth alongside it, born of the same primordial essence, and each waterbender a firebender. A counterpart. The spirit’s splitting energy had severed the bonds. In order to realize their true potential, a bender must subsume their counterpart’s element, defeat them and take their power inside themself.

At least, this is how Katara’s Gran-Gran explained it, and everyone after. She never had reason to believe any different.

-

Often at night, as Katara tries to fall asleep, she would picture the imaginary face of her future enemy. Sometimes he is stocky, hair shaved short with a cleft chin, his arms lined with scars from the war. Sometimes she is lithe, quick as an arctic fox, running circles around Katara in her mind. Their faces always have one thing in common, though: their golden eyes, blazing as hot and steady as the embers of the fire her tribe keeps lit all winter. It isn’t a shade Katara has ever seen before in anyone she knows, and yet she can’t shake it, the idea of how they might look.

When she meets her counterpart, she will know them by their eyes, Katara decides.

-

Master Pakku tests them periodically on their waterbending progress. There aren’t many women in her classes; Katara learns from one of the few others that the majority of Northern Water Tribe women remain in the city their whole lives, never mastering their own element, content to heal minor scrapes and patch the icy buildings when needed. Her Gran-Gran had had to call in a special favor to even let Katara be admitted to the waterbending classes. It angers Katara, but she learns to channel that fury into precision and power.

She wins every fight.

Pakku notices. He takes her aside one evening, nearly two years to the day after she’d first set foot in the North, and fixes her with a stern expression.

“You’re only seventeen, and yet you’re nearing the end of what I can teach you.”

Katara nods. “I’ve been training in the evenings on my own, too. I want to leave as soon as I can. I’m ready.”

“You’re not.”

“You just said I’ve learned everything there is to know. My tribe needs me, Master Pakku. I can’t waste more time here.”

“I said that soon _I_ will not have more to teach you, Katara,” her teacher retorts. “Do not mistake that for reaching the end of your learning. We have never sent a student to meet their match before they are eighteen, and it seems you must still master the art of patience.”

She isn’t happy about it, but they are already breaking with decades of tradition by allowing Katara to train in their tribe. She waits.

A fortnight before her eighteenth birthday, Sokka and her grandmother arrive at the North Pole, Gran-Gran solemn and Sokka bursting with energy. “They said you would be leaving soon,” Sokka says. This is news to Katara, but she welcomes it, forcing her brother out of bed once the moon is up to run drills with her on the icy plains surrounding the city. At first, he goes easy on her. It doesn’t last long.

-

On the morning she turns eighteen, she is woken by her grandmother. Kanna is smiling gently and holding a new tunic for Katara, thin and short and sky-blue. “I have a feeling where you’re going next, you won’t be needing a parka,” she says.

She does a good job of feigning excitement, but Katara knows her Gran-Gran, and she can see right through it.

Pakku appears at their door at midday. He is flanked by two warriors, fully dressed in ceremonial garb and wolf hoods. All he says is, “you’re ready.” The words send nervous energy thrumming through Katara, as if her veins had been set alight.

She’s not sure where she expects them to lead her, but it’s certainly not up, past the icy palace that she’d only set foot in once, the path winding farther still until the city is nothing but gleaming diamonds below them. Pakku stops before they reach the archway at the end. Beyond it, Katara can just make out flashes of verdant green, more than she’s ever seen before in her life.

“You must go in alone,” her waterbending master tells her. “Focus on the pond and allow yourself to become one with your element. Do not emerge until you’ve located your opponent.”

“How will I know when I’m done?” asks Katara.

Pakku makes an expression that, on anyone else, might be called a smile. “You’ll feel it.”

She takes a step forward, but before she can pass through the archway, Pakku’s hand snakes out to grab her wrist. “Katara, once you begin, you cannot stop the process. There will be nowhere for you to run, to hide. Do you understand?”

The knot of fear in her throat has swollen too much for her to respond. She nods.

Calm washes over her as soon as Katara sets foot in the oasis. Gentle splashes emerge from the pond at the center, so quiet she can barely hear them without straining her ears. She looks to the south, to try and see the spires of the palace, but the rest of the Northern Water Tribe is blocked from view by the trees encircling the space; it’s as if she has stepped into another world entirely.

Tentatively, Katara lowers herself to the grass in front of the pond and folds her legs.

It takes a moment for her to notice them. They circle each other, head following tail, as if locked in an eternal chase – or a dance of sorts. They are mirror images of each other, in reverse, all the spots that are dark on one koi light on the other. As she concentrates, they seem to speed up, blurring into each other so that Katara cannot tell where one ends and the other begins.

When she looks up again, it is night.

There had been no disturbance, but she feels suddenly on edge, as if there is someone standing directly behind her in the shadows. When she glances over her shoulder, the oasis is as empty and tranquil as ever, but she cannot shake the feeling that there is _something_ there. Her skin is suddenly, feverishly hot.

Steeling herself, she looks back down into the depths of the pond, where the two koi are waiting. Their movements are growing frenetic. The splashes are so big now that water droplets mist her arms, glittering in the moonlight.

Katara closes her eyes.

For long minutes, she only sees darkness, the veins on the insides of her eyelids translucently imposed across the void. Then, unbidden, in the distance: two suns, blazing.

Eyes.

She waits, and they come into focus, drawing closer through the black. For the first time, she notices the right is smaller than the left, the pupil dilated. Vaguely, as if her body is somewhere in the distance far behind those eyes, she can feel her heartbeat speed up, beating a double-time rhythm. She is warm, very warm, so warm she thinks she might be sweating.

The eyes blink, and the world bursts into flame.

Katara cries out, scrambling back, but when she opens her eyes the world is the same. The koi, unfazed, have returned to their tranquil pace, as if nothing had ever happened; the moon above her shines just as brightly.

Except now she can feel it in her chest, as if her body is being pulled forward by a hook lodged just behind her heart: an ember. A pulse.

A direction.

-

She has to wait three days before she can leave the North on a trading ship, and every moment of them is agony. Now that she can feel him (and she knows it is a him, can see the shape of him forming in her mind, growing out of the fog of urgency) it’s as if Katara cannot stop thinking of him for even a second, even as she tries to savor her last few days with her brother and Gran-Gran. She does not know when she will see them again – _if_ she will see them again – and it scares her more than anything. It scares them, too, she can see; Sokka tries to hide behind his veil of humor, but she can see right through it.

But even though a part of Katara is terrified, a much bigger part is ready to face him.

The ship is headed south, to the Earth Kingdom. The feeling in her chest is no more than a vague direction – _here,_ her heart tugs her, _this way_ – and the word is vaster than she could ever imagine, but she will find him eventually, the way that Pakku found his match. And besides, he may be looking for her, too.

The morning that she leaves dawns bright and unseasonably warm. There is one other waterbender seeking to master his element who leaves on his own mission with her; he is a few years older, his face already inked and lined with training scars. Before they board the ship, he is engulfed in a crowd bigger than Katara’s whole village, all cheering him on.

She looks to Sokka and her grandmother and her heart sinks.

“You’ll do great, Katara,” Sokka says, but his voice is wavering. “Just…do your wave-y thing. You know.”

His hug, when he pulls her in for it, is bone-crushingly tight, and Katara can feel his breath come heavy against her ribs.

Once she is onboard the ship, the Northern Water Tribe fades so quickly it nearly takes her breath away. The traders bustle around her, filled with a sense of purpose, and yet it hits her: for the first time in her life, Katara is well and truly on her own.

Every wave they cut through brings her one bit closer to her goal. Her heart begins to burn.

-

When the ship arrives at its destination nearly a full moon later, the captain takes Katara aside and asks her if there’s any more he can do to help her. She smiles as she shakes her head. It slips off her face as soon as she turns away.

They had let her off in a moderately-sized town halfway down the Earth Kingdom coast. The world around her is a foreign swirl of color and noise; she barely knows where to turn. All of her worldly possessions are strapped to her back. The blaze that sits above her ribs urges her onwards.

Before she had left the North, her Gran-Gran had pressed a small purse into her reluctant hands. “Our tribe has saved up for this,” she had told Katara. “Please take it. Use it however you need – whatever will make it easier for you to do what you need to do.”

She still feels guilty about it – the bag only holds a handful of coins, but it’s still enough to feed her people for six months or more. Katara cannot deny that it comes in handy, though. She finds a menagerie at the edge of town and purchases the fastest animal they own, a sleek hound the color of inky midnight. It may not share her heartbeat, but when Katara points it in the direction of the pull and whispers “go,” it does as she says. She clings to its neck, exhilarated, as forests and rivers and mountains whip by.

Even when they stop at night, once it’s too dark for even the xirxiu hound to see, Katara finds it hard to sleep. Her pulse continues to urge her onward: _go_.

-

They run until, suddenly, they don’t.

Katara has had a sneaking suspicion that they were growing close for days before they arrived at the grassy plain. She doesn’t think there is much more her body can take; the fire is everywhere within her now, pulsing behind her eyes and in her feet and her stomach and her palms, consuming her entirely. It reaches a fever pitch as her xirxiu hound breaks through the sparse barrier of trees ringing the moonlit plain. It is so strong it nearly blinds her with bright white heat.

She feels him before she sees him, because all of a sudden, it all drops away.

There is blissful silence. Her vision, moments earlier blurry with frenetic energy, is crystal clear, and it’s why Katara can see his form silhouetted against the moon, his hair ruffled in the wind. He is alone. As she watches, he turns toward her. 

It’s not her heartbeat, but her feet drawing her toward her counterpart now. A thousand different emotions flit through Katara’s mind – relief, curiosity, and, dominating all else, fear. But he doesn’t make any sudden movements; his footsteps are measured, and when he is close enough for her to see his familiar golden eyes shining through the darkness, he stops. They stand in silence for a long, tense moment.

“It’s you,” he says finally.

Katara nods. Her mouth is too dry to say anything.

“We—” The man breaks off, shaking his head, and then presses his palms together and folds at the waist. She can barely see his face through the shadows, but she thinks, maybe, for the briefest time, she saw regret there.

Then he ignites.

It would be spectacular if he weren’t so terrifying. The night air all around his body is rent by golden-red flame, bursting toward Katara from every direction, illuminating the field as clearly as if it is midday. The heat knocks Katara breathless, and she stumbles back, grasping for anything she can use to fight back. She should have been more cautious – her opponent needs no source for his attacks, but she is defenseless here, stranded high and dry.

Except she is not. Beneath their feet, she can feel it pulsing, calling out to her, so much water that it makes her heady with its power. It can’t be anything but the ocean itself.

Katara takes a hold of it with every fiber of her being and pulls.

The water crashes up over the side of the cliff, dousing the field and all of its flame immediately, and she allows herself a small smile. She may have been reckless, but the firebender had been downright foolish, waiting for her in a place like this. The tides wait at her command. She can practically hear them whispering to her: _come, take us, crush him, daughter of the waves_.

And so she does.

As the water bears down on him, the firebender flings his arms wide, and a sheet of flame flares across the dry grass. Katara’s wave evaporates on contact, but she has another at the ready, and it catches him off guard, tumbling in from his right. The firebender stumbles, but does not fall.

She aims a web of ice at his feet, but he jumps before Katara can ensnare him, leaping high into the air and kicking twin jets of flame at her as he falls backwards. It is too close – she feels them fly by her head, and the scent of singed hair fills her nose. Her ice shield has melted in her hands. He is coming closer now, not quite running, his hands encased in whirling flames.

Never before in her life has Katara seen so much fire at once. She understands, now, the flaw in Pakku’s training: she can run as many drills as she wants, duel the fellow waterbenders as often as she would like, but it will never come close to this, to the feeling of heat all around her, forcing her own element into the amorphous air where she has no chance of getting it back. The man _moves_ differently. It’s like nothing she could have imagined, and, if she weren’t so determined to snuff it out, she could almost think of the fire as beautiful.

 _Her weakness is a double-edged sword,_ Katara realizes. She is unused to the way the man bends, but he is just as unfamiliar with waterbending techniques, with the versatility and quickness of motion and of the raw power the element holds. Fire is unpredictable; in the wrong hands, uncontrollable. She only needs to turn his weapon against him.

When he next begins to move, bringing his palms forward and leaning into his attack, Katara darts to the side. She sends the smallest whip of water trailing out across the grass. Right as the flames begin to leave his hands, she reaches out and pulls.

He overbalances, just as she thought. The flames leap upwards into the sky. All of a sudden, she feels like laughing.

He is on his feet before Katara can reach him, of course, but now she has relocated her confidence and she can feel the moon overhead and the tides below her working in tandem, each propelling her onward. Her opponent never seems to tire, but neither does Katara. When next he lets loose his jet of flame, she is ready.

The pillars of elemental energy sizzle as they crash against each other, but her water does not evaporate this time. Katara fights to keep it cool against the overbearing heat, pushes it back into the flame, which she can feel as solidly as if it were a door she must fight to open. Bit by bit, it gives way underneath her insistent strength. She grits her teeth.

Above them, she can swear the mist of molten air is turning the stars strange colors, painting the sky in shades of blue and red.

And then, all of a sudden, she can feel it give way. The man topples backwards, his arms giving out, and the water crashes over him. Katara clenches her fist just before it passes over his head, and the splashes stop abruptly.

She observes the man encased in ice with cool eyes.

Katara isn’t sure what she had been expecting, except for the golden eyes. She thinks she might have wanted him to be older, but he seems to only have a few years on her, if that. His dark bangs have come loose from their topknot and are hanging into his face. An angry burn scar covers the entirety of his right cheek, his right eye a golden ember glaring from within the folds of tissue.

He says nothing as she nears him. His head is hung, but his eyes are alert. He is not quite angry. Disappointed, maybe. Resigned.

“You’re stronger than I thought,” he spits out once Katara stops. “My mistake. I should have known the moon would empower you.”

“I—” Katara wets her lips. She knows what she has to do, of course, but somehow it’s harder now, after hearing what he sounds like. She cannot tear her eyes away from his scar.

“Aren’t you going to do it?”

A snapping sound rents the air. Katara pulls the icicle from the mass next to the man’s head; it’s slippery in her grasp, her palms too hot to hold it. She can smell him now, this close to him; he smells of smoke and grass and something else that makes her nose itch. A foreign spice.

“Wait,” he says as she lifts the dagger. “Before you do. I want to know the name of the woman who defeated me.”

She blinks. Against all reason, she can feel her cheeks begin to heat.

“It’s Katara,” she says.

“Katara.” The syllables of her name on his tongue sound stilted, but still velvety smooth. He nods.

“Well then, Katara. You might as well get it over with.”

She lifts the icy dagger and aims it at his chest. She doesn’t want him to suffer; he is her enemy by circumstance, nothing more. It is not his fault the universe dictated him to be on the opposite end of her element, and besides, he looks so resigned, watching her with knowing eyes. Such familiar eyes.

Katara lets the dagger drip through her fingers.

“What?” he asks.

“I can’t do it.” She walks a safe distance away before she lets the man’s icy prison melt, sending him cascading, spluttering, to the ground. “Not like this. When I beat you, it will be in combat, and on a fair playing field. I will not earn my waterbending this way.”

He pulls himself to his knees, but no further, and watches her warily. He must still expect her to have some trick – as if she’d need one, when she had him pinned moments earlier, but maybe he worries that Katara is vindictive or cruel. She puts her hands up and tries to affect a neutral expression.

“I will face you again, and soon. But not tonight.”

She tries her best to ignore the flame that reignites in her chest as she walks away.

-

It torments her all day, to the point where Katara cannot sleep except for fitful bursts, can barely stomach food and water. She curls up under a banyan tree with her xirxiu and tries her best to let the dappled light lull her to sleep, but all she can achieve is a sort of agonized trance. She had planned, initially, to wait a few days and gather her strength before facing her opponent again, but she realizes now that she cannot go that long. It will have to be today, or she thinks she may awake to find her chest charred and caved in.

It’s during one of these moments of not-quite-sleep that Katara realizes she hadn’t even thought to ask the man his name. A shame; it would have been useful to have something to call him in her mind, instead of just ‘counterpart.’

( _Soulmate,_ a small voice whispers from somewhere in the haze of her sleepless mind.)

When the sun begins to descend, Katara rises, stretches, and forces down as much seal jerky from her pack as she can manage. They hadn’t set a time or anything so formal when she had left the man last night, but she knows, instinctively, that she will find him in the field at dusk; she had wanted a level playing field, after all. Neither the sun nor moon will offer them an unfair advantage.

She does not allow herself to stop and meditate on the man herself. If she does, she will be forced to confront the fact that she had let him go for reasons that even Katara does not yet understand. She had known, looking into his eyes, that if she killed him in cold blood while he was defenseless, it would be a stain on her soul that she could never remove, no matter how many lives her healing could save.

When she arrives in the clearing, he is waiting for her.

“You came,” he calls out as Katara walks forward, already gathering the water from the nearby ocean to her.

“Did you think that I wouldn’t?”

“I don’t know,” he says. “You’re not what I expected.”

Even as Katara opens her mouth to form the question, she can feel that it’s a bad idea. She does not need to humanize this man to her any more than he already is – it will just make everything harder. But she can’t help it.

“I told you my name last night,” she calls. “Don’t you think that it’s only fair I know yours?”

The man stills.

“Zuko,” he says.

Then he is aflame once again, and Katara can’t concentrate on anything else.

-

For the next three evenings, they fight to a standstill in the gloaming. There are moments, each time, where Katara thinks she may land the killing blow, but she always hesitates a second too long and they are gone. She cannot say what stills her hand – an impulse, something deep down in her stomach that she has to consciously fight against each time she spars with Zuko. Her body draws her to him, but against all her better judgment, it doesn’t want her to _end_ him, even though it’s her sole purpose. Even though once she does, she can finally go home.

There are times, too, when she is sure it’s the end for her, when the fire is bearing down from every direction too hot to fend off, and she very nearly succumbs but when she blinks, it’s gone.

Katara worries that she is reaching her breaking point. She still cannot find a satisfactory way to rest; whenever she isn’t in sight of Zuko, the blaze inside her begins anew, and it feels stronger every time. By the time she reaches the clearing that has become their battlefield each evening, it is all but unbearable.

And yet she still can’t find what she needs to end it.

The fight is wordless each night. Katara is beginning to forget how it feels to hear another human’s voice; sometimes, during the day, when she cannot sleep, she tells herself stories just to remember how to speak, and the intensity of the blaze cools somewhat as she does. She is beginning to wonder if Zuko is no more than a feverish figment of her imagination.

It might be this curious theory that drives her to open her mouth when they are both so thoroughly exhausted at the end of their fifth night of fighting that neither can stand. It might be this, or it might be Katara’s strange longing to hear his voice again. She will not admit it either way.

“Can you sleep?”

Zuko startles, suddenly alert whereas he had been drowsy moments earlier. “What?”

“When you leave here, can you sleep?” Katara repeats. “I can’t. When I’m away from you – from here – there’s something in my body that makes me so anxious. It’s like a fire burning in my chest.”

He takes so long to respond that Katara begins to wonder if she should just leave, but then –

“It’s like I’m drowning.”

“Drowning?”

He nods. “I can’t breathe right. I can never get enough air into my lungs. And there’s a rushing sound, in my ears, and it stops me from concentrating on anything. It’s…aggravating.”

“ _You carry a part of them within your soul,_ ” Katara says softly to herself.

“What did you say?”

“Oh.” Katara flushes. “I didn’t think you would hear that.”

“What did you mean by it?”

“It’s the story my Gran-Gran used to tell me to explain what I would need to do to master my element. How to find my – you.”

Slowly, Zuko pulls himself into a seated position, his legs crossed in a lotus shape. “A part of your soul,” he muses.

Katara nods. “All of the elements were one, once upon a time. They were never meant to be separate. When you defeat your counterpart, you’re reuniting them.”

“Wouldn’t _meeting_ your soulmate be reuniting them?”

They both freeze. Neither of them had ever said the word to the other before; Zuko absently lifts his fingers to his mouth, as if shocked he’d let it leave his lips.

“I don’t know,” Katara says. “That’s just the way she told it.”

“I heard, once,” says Zuko, “about a master firebender who didn’t defeat her counterpart. She lived with her until their dying day. They found peace, somehow, as long as they stayed together.”

The night stretches long over them, crickets chirping in the distance, as Katara mulls the words over.

“It sounds like a myth,” she says finally.

“And besides, it would never work.”

“Definitely not. I’d imagine you don’t like snow much.”

“And you probably wouldn’t enjoy the palace.”

“The _what_?”

But Zuko has vanished into the night once again, leaving her reeling under the light of the rising sun.

-

Then comes the night where he defeats her.

It starts out no differently than the many other evenings they’d sparred to a standstill. If anything, the scales are tipped in Katara’s favor; the air is muggy with the promise of rain, so thick that she can wick moisture from all around them, creating clouds of roiling steam that obscure Zuko’s vision.

He has an uncanny amount of energy, though, and keeps her locked in battle far past the point when they would normally have both collapsed. Katara finds herself on the defensive for most of the night, her ice shields all dissolved as soon as she can form them, and she can’t get a handle on the firebender – he is too quick, flying about the clearing on fire-sped feet at double her own pace.

When he catches her, it’s from behind. Katara is so focused on maintaining the mist that she doesn’t see him coming until he has his hand at her throat.

“Got you,” he drawls into her ear.

Katara feels her body wrack with shivers. _It is_ not _the time_ , she tells herself, and certainly not with _him_. And yet.

She spins out of his grasp. He lets her go easily, watching her with those inscrutable golden eyes, and even though Katara is right next to him her skin feels just as hot as it ever had in the throes of her hunt.

“Clever,” she says begrudgingly.

Zuko shrugs. “I’ve fought you enough to learn where your weaknesses are.”

“You could have ended it.”

“I could have,” says Zuko, his tone even, betraying nothing.

“But you didn’t.”

“You spared me once,” he says. “To kill you without repaying that debt would be against my honor.”

But Katara has gotten to know him, too, across the span of the nights they’ve shared, and she knows now that Zuko is not being entirely truthful with her. When she searches his face, he refuses to meet her eyes.

“So if this were to happen again, you wouldn’t offer me the same mercy, hm?”

“It’s getting late,” Zuko says instead, apropos of nothing. “The sun will be rising soon.”

Katara turns her back on him, her thoughts tangled into a knot of confusion and anxiety.

“Would you like to have tea with me, Katara?”

She stops short. There are sirens in her head warning her not to turn around, no matter what.

“Yes, Zuko,” she answers. “I’d like that.”

-

For the week or so that they’d been meeting to fight each other each night, Katara had assumed Zuko had set up a makeshift camp outside, like her. She’s shocked to discover how wrong she was. Zuko leads her through the wavering predawn light to a small cottage tucked away on the other side of the forest, all dark wood and red curtains and a sweet little stone pathway leading to the door. It’s nothing like what she would have expected of him, but it’s charming. Peaceful.

“Do you…live here?” Katara asks, picking her words carefully. “Alone?”

Zuko laughs. It’s a throaty, rough sound, but oddly pleasant, like a lungful of too-cold air. “No. I bought it. I wasn’t sure how long I’d be here waiting for you.”

“Waiting for me?” Katara frowns. “Didn’t you feel the pull, too? I thought you were seeking me out.”

“I felt it. But I didn’t want to be caught unaware. I chose this place for us. It seemed fair – water on one side, plenty of open room and dry grass for fire to catch.”

The longer Katara stays near him, the less about the whole situation happens as she thought it would. She feels as if she’s been thrown violently off the path she was following – the one her family and Master Pakku and her whole tribe had laid out for her – right into the ocean, and now she’s treading water just to stay afloat.

“Who are you?”

It’s far from the first time she’s wondered it, but it’s the first time she’s put voice to the question.

Zuko extracts a small key from his tunic and pushes it into the lock. “It’s a long story.”

“Who you _are_? Come on, Zuko. How did you afford this place? You can’t be much older than I am.”

The interior is dark, swathed in rich fabrics and smelling of smoke and incense. It doesn’t feel musty, though, the way that so many wooden buildings do to Katara; instead, it’s almost comforting, especially when Zuko sends tiny balls of flame into sconces affixed to the walls. It’s the first time she has seen him firebend when it’s not directed at her.

Zuko waves a hand at the small trestle table tucked into one corner. “What tea is your favorite? I have most kinds. My uncle wouldn’t let me leave the Fire Nation without a year’s supply.”

“Does your uncle live in the palace, too?”

“He did.”

“And that’s where you live when you’re not here?”

“You didn’t answer my question about the tea.”

“Well, you didn’t answer my question about who you are.”

Zuko chuckles again. The sound sends shivery sparks cascading down Katara’s neck. “Fair. I’ll make you jasmine.”

When he turns his back, Katara doesn’t sit where he had indicated, but instead lets herself wander around the rest of the large room that makes up the cabin’s interior. Despite the Earth Kingdom’s temperate weather, there’s a large hearth dominating one wall of the space, and a pair of wickedly curved swords lay across the divan. It’s otherwise sparse – no hints at Zuko’s personal life besides a pile of saddlebags in one corner and a few scrolls spread haphazardly across a desk. Only one of them is facing upwards. Katara sidles over to it, sneaking glances at the entry to the small kitchen from which Zuko’s voice emanates.

The face-up scroll seems to be a letter, written in flowing calligraphy. Katara squints at it. She had never been good with the formal script, but all she really needs to understand are the first words: _Dear Prince Zuko…_

“Katara?”

She spins around, shoving the scrolls behind her. “Hi!”

“Hey.” Zuko holds steaming cups in both hands; he holds one up toward her. “I made you tea.”

The scent wafts across the room, fragrant but with a decidedly bitter undertone. Katara sniffs. “Did you put poison in that?”

Zuko rolls his eyes. “All these nights of fighting, and you think I’d have to resort to _poison_ to end you?”

“That doesn’t smell like just tea.”

“I’m not a tea master, but I promise it’s drinkable.”

Katara hums, but takes the cup from him anyway.

“So,” Zuko says when she’s taken her first sip – bitter, yes, he’d definitely burned it, but not poisoned – “I saw you were looking at my letters. Find anything interesting?”

Katara spits her mouthful back into her cup. “I wasn’t—”

“I would be curious, too.”

She waits a moment, watching to make sure he’s not truly angry, before asking, “Prince Zuko?”

“Yes.”

“Prince of what?”

Zuko says, “The Fire Nation.”

She must have heard him wrong, Katara tells herself, or else he must be joking, except his gaze is even and there’s no hint of amusement on his face. She hadn’t misread the letter.

“The whole thing?” she asks, feeling faint.

“I hope so, unless something has happened since I’ve left.”

“That’s not funny, Zuko. You’re a—” She can’t even say it. “And I have to _kill_ you. Wouldn’t that make me an enemy of the Fire Nation?”

“Not if I kill you first.”

She wishes she could ask to lie down, step outside, _something_ , but Katara feels rooted to the spot. _The Prince of the Fire Nation is her counterpart._

“Why didn’t anyone else come with you? Soldiers or something? You could have overwhelmed me easily. You could have caught me off guard before I even got here.”

“Why would I do that, Katara? A victory without honor is worse than no victory at all.”

She’s about to object, but then she remembers the night she had met him, the mysterious impulse that stayed her hand.

“You’re not at all what I expected,” she blurts out. “I don’t know what I _did_ expect, but it wasn’t…this.”

Zuko shrugs. “You’ve got bad luck. I imagine you’d be able to beat any other firebender who wasn’t trained from childhood by ancient masters. You’re strong, Katara.”

“Not that it matters,” she mutters.

“What?”

She flushes, hating whatever it is about the firebender that lowers her inhibitions enough to put a voice to all of her well-guarded worries. “Even if I fight well, it doesn’t matter. That’s not what I’m meant for.”

“What _are_ you meant for, then? Why are you trying to become a master?”

“My village,” Katara says. “I’m the only one who can save it. We haven’t had a waterbender born into the Southern Water Tribe for generations, and if I can’t master my element, I can’t become the healer my people need.”

Zuko, to her surprise, looks taken aback. He works his jaw, his gaze steady on her face, darting down only briefly to her hands wrapped around the teacup.

“And if you don’t return from this test?”

“Then our tribe will likely die out,” says Katara simply. “The winters are growing harsher, and more and more of our men come back from the hunts and battles with incurable wounds. It was a risk, coming here, but one I had to take.”

Again, his gaze darts down from her eyes, but this time it lands somewhere much higher. Katara reaches up to touch her lips, feeling them burn with the intensity of his stare.

“You’re not what I expected either, Katara.” His voice is husky. “Not at all. I—”

 _You feel it too,_ Katara wants to say. _You feel this strange heat. You want it, too._

“I think you should go.”

“What?” Katara startles.

“It’s getting light out. You need to go.” Zuko stands abruptly, jarring the table and making the teacups splash lukewarm liquid. “This was a mistake.”

As quickly as the desire had entered Katara, it drains out of her, leaving only confusion and hot, seething anger. She draws herself up to her full height, schooling her face into an expression as cold as the ice caps on the longest night of the year.

“Fine. I’ll see myself out, then.”

“That’s not—Katara, I’m sorry.”

He reaches for her just as she’s about to open the door. His hand around her wrist is gentle; she could break his hold easily if she wanted, but she _doesn’t_ want to, doesn’t think she even can with the way her entire arm has been set alight, shivers running up and down her tendons and every hair standing upright. Zuko’s mouth falls open in a slight ‘o’. Katara cannot tear her gaze away from it.

“This isn’t how I wanted it to go,” he murmurs.

“I understand,” she says, and hates how instead of a glacier, her voice has become as fragile as a thin sheen of ice over a pond. “We’re enemies. We can’t be anything other than that. It’s not how this works.”

“I wish it were different.”

He raises his other hand, his movements slow enough that Katara can guess what he’s doing, can pull back if she needs to. She doesn’t. Zuko cradles her cheek in his palm, and she turns into it, feeling the heartbeat at his wrist throb strong against her lips.

“I wish it were different too,” she whispers.

Tearing herself away is the hardest thing she’s ever done – harder than leaving her home for the Northern Water Tribe, harder than suffering the constant jabs from the male waterbenders as she trains, harder than being defeated by Zuko that night. When she rips herself out of his grasp, it feels like something in the air rips, too, a cosmic energy severed.

He watches her go silently, his golden eyes a beacon in the dawn.

-

Twelve hours later, she waits for him under the weak light of the waning summer moon.

Katara hadn’t been able to sleep, her thoughts flying in a thousand different directions every time she closed her eyes, and she wavers on her feet now as she waits. She wants to be ready. To catch him before they begin their nightly ritual. The way they had parted had left her with so many more questions than answers, and this time, she will not let Zuko get away with half-truths and crypticisms.

It’s already later than she had expected; they’d never made a formal agreement to meet here every night, but she’d come to expect to find Zuko there and waiting as soon as the sun went down, like clockwork. The deviation from routine puts Katara on edge.

 _Maybe he couldn’t sleep, either,_ she justifies to herself. _Maybe he needs time to think_.

A rustling from the trees at her back startles her, and she whirls around, tensing up.

 _An animal. It must be_ —

Zuko bursts from the forest, both hands alight. Through the blaze, Katara catches a glimpse of his face: tortured, determined. She thinks that tears may glint at the corners of his eyes.

“I’m sorry,” he cries, and then he dives for her.

Katara screams. Her brain is rushing to keep up, even as her hands weave an icy shield to block the flame: Zuko had ambushed her, is scorching the earth with wave after wave of flame now, all of it directed right at her. _I’m sorry._

She had always known how dangerous Zuko and his element were, but somewhere in the past few nights, she had started to forget. It had begun to feel more like her sparring matches against the waterbenders at the North Pole than anything else: strenuous, yes, but never deadly. Now, the flames are rising over her head, tall enough to consume her effortlessly.

 _I’m sorry_ , he had said.

“Zuko!” she yells. Her shield sizzles and buckles under the onslaught of fireballs. “Stop! We can talk about this!”

His only response is to grit his teeth and punch harder.

Katara dodges between the careening orbs of flame, reaching out desperately for the ocean, but so much of the water evaporates into the heat before it can reach her and she can barely form anything of substance while running so quickly. No sooner does she duck behind a rocky outcropping than a jet bursts over her head, singeing her hair and filling her nose with acrid smoke.

Something had happened. She doesn’t know what, and at this rate, she can’t expect Zuko to tell her, or do much of anything except wordlessly attack. Neither of them had ever retreated mid-fight before, but she can’t face him like this – he’s agonized, enflamed. A loose cannon. The moon isn’t nearly strong enough for her to expect to overpower him.

“Zuko!” she cries again, detesting the way her voice cracks. “ _Please!_ ”

Footsteps grow closer. Her heart is in her throat. Before her, the ocean stretches out, and Katara silently wills it to her, a thousand tiny tendrils creeping up to heed her call.

She can hear him breathing now. He must be waiting for her.

There’s no reason to hide, though – nowhere for her to go, unless Katara takes a leap of faith straight into the ocean. She closes her eyes, steels her nerves, feels the pulse of the water below her until it attunes with the flow of the blood in her veins, becoming one and the same.

She stands, and she is met with pure, blinding heat.

It rips up her left arm, hotter and more painful than anything she’d ever felt before, so much so that at first she can’t even tell what’s happening. When her vision clears, Zuko is frozen, his mouth open in shock.

She doesn’t wait for him to make another move. She runs, the tears ripped from her eyes and disappearing into the night.

-

For two days, she disappears from the world.

The forest takes her into its vast embrace, tucking her away in the roots of a banyan, cradling her as she heals her arm bit by bit through clenched teeth. But even as the burn fades from her skin, the fire in her chest grows, leaping outwards, consuming Katara until she can barely move. She understands, finally, what Pakku had meant: there is no way to stop this without defeating Zuko. He is her purpose, now. Her destiny.

She staves it off for two whole days, two scorching sunrises and two tortured nights underneath the dying moon. She does not sleep. She cannot force food down her burning throat. All she can take in is water, the momentary relief it offers her when she has it in her hands or her mouth small moments of bliss. The xirxiu hound curls up a few feet away, watching the forest with sharp eyes; Katara understands that it’s a smart creature, that it is trying to protect her as best it knows how, but it has no way to save her from what she most needs saving from. Only Katara herself can do that.

On the third night, it becomes clear: Katara will have to take matters into her own hands.

Through the delirium of fever, she drags herself to the xirxiu, half surprised Zuko hasn’t come and hunted her down in her weakened state already. The hound seems to understand; it bends down, allows Katara to slide onto its back, locking her arms around its neck. It’s not dignified, nor particularly comfortable, but Katara has to do it now, while she still has the strength to hold on.

“Zuko,” she says weakly against the xirxiu’s sleek neck. “Find Zuko.”

Somehow, it knows what to do.

As the trees flash by, she realizes that they’re familiar; the hound is taking her back to the clearing, the same one they’d met in every night. She’d expected something different – his cottage, maybe, or even the shore, evidence the prince is retreating to his kingdom – but as they grow closer, she can feel the blood begin to beat stronger pulse by pulse in her veins, the desperate ache filling every corner of her body receding like a tide back into her core. She might just be strong enough to take him. She’s ready now.

And yet, still, there’s a part of her that recoils at the idea of driving that icy dagger into Zuko’s heart. It was easier before, when she hadn’t known his face, the timbre of his voice, to imagine killing her counterpart; it had happened a thousand times in her mind as Katara tried to familiarize herself with the idea. She’d had years to grow used to the fact that she would be a killer. She thought she was ready.

Even now, as the hound breaks through the last of the trees and into the bare starlight, she knows that she never will be.

At the center, on the rocky outcropping exactly where she’d left Zuko, a shadowy outline sits, silhouetted by moonshine. He is alert, but makes no move as Katara disembarks, the xirxiu retreating back into the forest as quickly as it had come as if it can’t stand to watch what happens next. Her footsteps are hesitant as she crosses the clearing.

“You came back,” he croaks.

Katara nods. “I had to.”

“You felt it too?”

“Of course. I thought I was going to burn up.”

“I couldn’t breathe,” he answers, and now she hears how much rougher his already-scratchy voice is, the words coming out scraped raw.

“And now?”

He shrugs. “Well, you’re here now.”

Cautiously, she takes a seat a few meters away from him, the cool grass tickling her ankles as she folds her legs. “I guess there’s no way around it, then.”

“There is,” Zuko says. “Being together.”

Katara draws a sharp breath.

“That’s a temporary fix. Neither of us are master benders.”

“Are you sure? Waterbend now, Katara. Anything. Just try it.”

She reaches out a hand and pulls a ribbon of ocean water to her, tamping down her skepticism.

“What’s something you could never do before?” Zuko asks. “A move, a form. Anything.”

“I—” Katara watches the water undulate, thinks of the Northern Water Tribe, racks her memories for anything, but she can’t.

“You said you needed it to be able to heal.”

She nods. “I can heal surface wounds, but nothing internal.”

“Fine,” Zuko says. “Heal me.”

She shakes her head, sure she must have misheard him. “ _You_? You’re not even injured.”

He gestures at his neck. “Believe it or not, choking on imaginary seawater for two days straight can do a lot of damage to a man’s throat.”

Katara doesn’t say it, but what she thinks is _You’d trust me_? _That close?_

He’d tricked her before. He could do it again, and easily. But if he’d wanted to kill her, he had ample opportunities already. His hands, now, are pressed together in his lap, and his posture is loose, unguarded. She thinks of his shock when he had burned her, of the way he’d let her go as soon as he had caught her the last time they sparred.

She rises and crosses the clearing to him.

This close, she can hear how ragged his breathing is. Every intake of air sounds painful, and Katara winces to hear it. Zuko chuckles, but it devolves quickly into coughs.

“It might not work,” she says quietly. “It hasn’t in the past.”

“It will.”

“How do you know?”

“Trust me, Katara,” he says.

And, against all instinct or reason, she knows that she does.

The water begins to glow blue in her hands, coating them, and Zuko’s mouth falls open in a small ‘o’ as Katara brings them to his throat. Even through the barrier of water, she can feel how warm his skin is. He swallows thickly, and his Adam’s apple bobs against her palm.

Katara closes her eyes and concentrates.

Her training in the North had never focused much on healing. Pakku had derided it as a women’s profession many times, reiterating how useless it would be when faced with their oncoming doom in the form of a firebender; Katara takes small pleasure in the knowledge that he had been wrong, and it had been more useful than he could have known not once, but twice. It means, though, that the shapes she draws the water in across Zuko’s throat aren’t frozen into her muscles the way her fighting katas are. Instead, it’s instinctual. And it’s oddly intimate – she can _feel_ him, not just his throat working against her hands, but the beat of his blood beneath the skin, the bones and the sinew and everything that makes him Zuko.

“Katara,” he murmurs, and his voice isn’t so rough anymore. “Open your eyes.”

She blinks.

It’s not just her hands glowing anymore. It’s the very air around them, filled with a blue haze that’s almost bioluminescent, seeming to radiate from their skin. Katara gasps.

“That’s—”

“It’s you,” Zuko says, and he sounds just as awed as she feels, except when she looks back at him, he’s not staring at the glow surrounding them, but at her.

She draws her hands away from his throat. The glow dims by degrees, but persists.

“I’ve never seen _anything_ like that before,” she says. Her voice comes out strained. “Not even my waterbending master could do that. I don’t understand.”

“My uncle told me, once, that there was another way.”

Zuko takes her hands in his. They hang between the two of them, linked, his rough and warm around Katara’s. She feels peaceful. Whole, somehow, in a way she never has before.

“I didn’t believe him at first,” Zuko continues. “I didn’t until I met you. The first night, when you spared me, I thought maybe we could try to figure it out together. But I didn’t even know where to start, and I was worried you would attack me for it. I apologize for that.”

“Why did you try to kill me?” Katara blurts out.

Zuko hangs his head. “I regret it, Katara. I should never have done that. There was a – a message from my father, telling me he knew that I’d found you and to stop playing around and finish the job. Or else – “ He shakes his head. “Well, anyway. I was conflicted, Katara.”

“I know,” she says, and she does. Even now, she can _feel_ him, somehow, feel his energy, the tangled knot of fear and desperation and strange hope that coils inside Zuko.

She doesn’t realize she’s said it out loud until he nods. “I do, too.”

“It’s not a waterbending thing?”

“I don’t think so.” He begins to trace his fingers over the backs of Katara’s hands, up the insides of her wrists, and she shivers despite the warm summer night. “You spoke of the legend your tribe has, about how to become a bender. My nation has a similar tale.”

“You have to take a piece of your soulmate’s bending into yourself to become a master. The piece that was lost when the types of bending were separated.”

“Right.” Zuko nods. “Everyone took it to mean that you had to kill your soulmate, to take that piece by force. But Katara, you _gave_ that to me just now. You gave me that piece of yourself.”

“That’s not – “

But it’s _not_ impossible. Not at all, the more she thinks about it.

“And I gave you a piece of myself, too, just now,” he finishes quietly. “No defeat required.”

“Just us.”

“Just us,” he agrees.

Katara wets her lips. She suddenly feels parched, the desire to be in the water rushing below them overwhelmingly strong. She doesn’t want to leave Zuko, but –

She reaches up, and a moment later, it’s raining.

Zuko’s eyes widen, but then, after a moment, he laughs. It’s a _real_ laugh, one from deep in his belly, a rich timbre like a musical instrument, and Katara finds herself laughing along with him, and then suddenly gasping, because Zuko has reached up through the rain and turned the sky above them golden with fireworks, sparks showering through the raindrops and mixing together and shrouding them in mist.

She takes him into her arms, shocked at how natural it feels as Zuko sinks into her. As if she’d known him once, and will continue to know him.

When she pulls back, the sky is clear once again. Katara feels translucent, as if Zuko can see every bit of her insides, but all he does is smile, staring at her in awe.

“What do we do now?”

(A lifetime later, when they are both old and gray and travel-worn, she will remember this exact moment as clear as a lightning flash, dividing the _before_ and the _after_ of her life. A lifetime later, she will remind Zuko of it over bowls of sea-prune stew and their laughter will warm the night air.)

Now, Zuko levels his gaze at her, what was once a burning fire now a dazzling warmth.

“We show people what it looks like,” he answers. “What we are.”

She knows it to be true. It’s the purpose she’s been unconsciously seeking her whole life, the piece she had been missing. And with Zuko at her side, she can’t imagine anyone being able to deny their strength.

“And what are we?” she asks, almost teasingly, as she reaches once again for his hand.

Zuko grins. “Counterparts.”

**Author's Note:**

> day two!!! this is the longest fic i did for this week, it totally spiraled out of control hahah
> 
> i wrote this just after finishing The Night Circus, which is one of the best things i've read this year - it was drawing from that a lot, with parts of the One Thousand and One Nights legend and the Greek myth of soulmates from The Symposium mixed in. it was an incredibly fun concept to make up lore for and i LOVED this prompt! (side note, how crazy is this zutara week?? the content has been off the chain and i am so impressed!!)


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